AirGap Vault
Installed on a smartphone that has no connection to any network
... is saved in the secure enclave of the device, only accessible by biometric authentication. Accounts for multiple protocols can be created. Transactions are prepared by the AirGap Wallet and then transferred to the offline device via QR code, where it is signed and sent back to the Wallet using another QR code. AirGap Vault is a hybrid application (using the same codebase for Android and iOS).